Race Area Location
A race area map is provided, featuring an arrow indicating the average wind direction for the race. Additional drawings are included when applicable to illustrate wind or current features, when those insights can be drawn from race analytics.
Start Line Data
Start Line Data Overview
The start line data provides a visualization of the line, including its length and bias. The wind direction shown is the one suggested by the app for the first few minutes of sailing and is based on the tracks of the boats after the start.
The other fields are described as follows:
• Line Dist at Gun: The distance to the line at the gun. Negative values indicate being over the line.
• Line Time: The time when the line was crossed. Negative values indicate crossing too early.
• Pos at Start: Position at the line; 0% represents fully at the RC (Race Committee) side, and 100% represents fully at the Pin side.
• Bias Used: The amount of bias used when crossing the line. If you start at the favored end, you are using the maximum available bias.
• DT Lead at Gun at 1:00: The upwind distance to the leading boat at the gun and after one minute of racing.
• SOG at the Gun: The speed over ground at the gun.
• Colored Dots: Show the position of tracking devices at the gun
The black dots represent the positions of the boats at specific times before the start and at the moment of the start.
Start Line Ends
The start line is determined based on how the information was provided.
If the start line was set using pings received with the logs from the sailing teams, keep in mind that these pings are taken at different locations and can sometimes be inaccurate. Many teams set these pings conservatively. Additionally, the start line ends can move as the boats swing around their anchors. In the worst-case scenario, such as when there is a current against the wind, even a slight difference in wind speed can cause the start line boat to drift significantly from its anchor position.
If the start line is not provided, the best possible approximation is used based on the available information (e.g., which boats were over the line, video footage of the start, etc.). However, this approximation may not always be perfectly accurate.
If the positions of the RC (Race Committee) and pin end were also logged, then the start line would be more precise, as their exact positions at the start would be used. This same accuracy applies to starts managed by the RaceSense system by Vakaros.
If the boats are sailing at high speeds and the GPS refresh frequency is low, they can cover significant distances between two GPS fixes. For example, a boat traveling at 20 knots moves approximately 10 meters per second.
GPS devices may also be positioned differently within each boat, which can affect their recorded locations.
Reaching Starts
For reaching starts, a green dot is added to indicate the closest point to mark 1. A dashed line extends from this point toward mark 1. On the data screen, the distances from this closest point, as well as from both ends of the line to mark 1, are displayed. These distances are also presented as a percentage of the shortest possible distance to mark 1.
Data Fields
The data fields display the average values for the selected period. All wind-related values are calculated based on the fixed wind direction set for that time frame. The table is generally sorted by time, with the best-performing boats for that period appearing on the left side. In certain sections of the report, these values may only represent filtered straight-line sailing, excluding maneuvers and mark roundings. In such cases, the table is sorted by VMG (Velocity Made Good) to highlight the best-performing boats on the left side. The background of the lowest value is colored red, while the highest value is colored green.
Time – sailed time
Dist – sailed distance.
Updist – upwind distance sailed.
Mans – maneuvers and cumulative loss in all of them (losses are in upwind meters)
SOG – speed over ground
VMG – VMG to the wind set.
ATW – angle to the set wind direction. In shifty wind, it usually shows who has sailed better shifts. In stable conditions, it shows the difference in the boat’s performances.
Heel – Heel of the boat (L – leeward, W – windward)
Heel TR – the amount of movement of the heel in degrees per minute. A higher number means that the boat was more unstable. This number can only be compared between the same logging devices and same logging frequencies.
GPS Tracks
The GPS tracks display the positions and paths of the boats, with the wind always coming from the top of the screen. The wind direction is set based on the GPS tracks for that period. Horizontal lines indicate the current upwind position of each boat for easier comparison. If boats are highlighted, the upwind distance in meters will also be shown. The number next to each boat’s name represents its current speed which can be noticed by “Val:SOG” at the top right.
The GPS track is colored to highlight performance: the top 10% of sailing is shown in bright green, while the bottom 10% is in bright red. Green shades represent performance better than 50% of the time sailed, and red indicates worse performance. The path is primarily colored based on VMG (Velocity Made Good) relative to the set wind direction. If a different value is used for coloring, it will be specified on top left corner of the image.
The race geometry shows the angle of the next mark relative to the wind direction. In this example, the mark is 10 degrees off, resulting in 1.72 times more sailing on the starboard tack. Laylines are also drawn based on the typical angle of the boats on that leg (33 degrees in this case).
Maneuver Performance
When not too many boats are racing, maneuver performance is calculated for each tack or gybe. The numbers displayed along the path can indicate either the upwind/downwind meters sailed during the maneuver or the maneuver loss.
• Upwind Meters: This value shows the upwind or downwind distance sailed during the maneuver. A higher number is better, making it easy to compare performance between boats.
• Maneuver Loss: This measures how many meters a boat loses by performing the maneuver, compared to not tacking. It calculates the VMG (Velocity Made Good) before and after the tack, and compares it to the VMG during the tack. However, this number can be less reliable due to the variability in conditions before and after each tack. For instance, if a boat was sailing slowly before the tack, the loss might even appear negative. Similarly, a boat performing better before and after the tack could show greater loss compared to a slower boat, even if their in-tack performance is similar.
The maneuver numbers also help in visualizing the data on the graph. Vertical lines in the Graph window represent maneuvers, and the numbers displayed above them correspond to those shown in the GPS path window.
Polar Graph
The polar Graph shows all the points of the selected period for all the boats. The wind always comes from the top. Each point is drawn at the angle and speed the boat had at that moment. The further from the center, the higher the speed. The VMG (Velocity Made Good) and performance is better the higher up the screen the dots are on the upwind and the lower they are on the downwind.
The example above shows the blue boat sailing at a low angle upwind on a starboard tack, resulting in a lower VMG.
Graph Screen
Graph screen most of the time shows one of these values:
TTL (Time to Leader): This metric shows how many seconds earlier the leading boat was at a given point in the leg. TTL remains stable even at mark roundings but can increase or decrease with changes in wind speed.
DTL (Distance to Leader): This measures the distance, in meters, between a boat and the leader at a given time. The DTL can fluctuate significantly during mark roundings, especially if boats are sailing much faster upwind than downwind.
SWD – Suggested Wind Direction: The app analyzes the race and estimates the wind direction for each time interval based on the boats’ tracks. The accuracy of the wind direction improves with the number of boats participating in the race.
Dashed vertical lines are the mark roundings. Solid vertical lines are maneuvers (not shown below since there are too many so they are hidden)
Mark Roundings
Mark roundings are typically shown with a GIF animation and a screen displaying data for the distance to and from the rounding point. All logs are aligned along the same upwind line, so boats rounding the favored mark cover fewer upwind meters. For example, in the illustration below, the black boat covered approximately 50 meters less upwind, indicating that the rounded mark was favored by 25 meters. Additionally, the black boat completed the 100 meters to and from the mark 12 seconds faster than the green boat. The DTL graph shows that the black boat overtook the blue boat by rounding the favored mark, while the blue boat was still sailing downwind.
The wind direction for mark rounding is generally determined based on the first few minutes of upwind sailing after the rounding.
GIF animations
GIF animations are generated for each leg of the race. When necessary, the upwind distance between two selected boats is also displayed. Additionally, animations are created for the start, including a countdown, and for mark roundings as needed.
